It's one of the biggest TV events of the year, watched by around a third of the British population.

But as the X Factor final kicked off last night, the talent show was accused of straying somewhat from its family viewing credentials as Christina Aguilera and Rihanna put on two extremely provocative pre-watershed performances.

Aguilera wore an very low-cut black dress as she cavorted with an army of lingerie-clad dancers while Rihanna thrust her way through her solo performance in pants and strapless bra.

Scroll down to see video of the performances...

Raising eyebrows: Christina Aguilera puts on a provocative display as performs Express from her new film Burlesque on the X Factor last night

Pre-watershed: Rihanna also set temperatures racing as she stripped down to fishnets, pants and a strapless bra. The performances from the two singers prompted a flood of outraged viewers to take to Twitter

The superstars jetted in from the
States to appear on the show, with Aguilera duetting with Rebecca
Ferguson and Rihanna supporting Matt Cardle.

But
it was as they took to the stage for their second respective
performances of the night - before the 9pm watershed - that they raised eyebrows, leading to Twitter and internet forums being flooded
with comments from outraged viewers.

Ofcom were not available for comment
today but the outrage at the racy performances will no doubt lead to
hundreds of complaints.

The X Factor has already had 3,215
complaints lodged with the regulator making it the most moaned-about
show this year, with no other programme coming close to talent show.

Mary Bryne and Treyc Cohen's exits led to floods of complaints, while many viewers were angered when
Gamu Nhengu failed to make it through bootcamp.

Last-minute changes to the format have meant that some viewers have been left out of pocket betting a record £15million on the show this year, learning of rule twists after their bets had been placed.

Inappropriate: Christina and her backing dancers, dressed in stockings, suspenders and lingerie, thrust themselves against their chairs

But last night the angry attention was focused on Christina's performance and viewers shared their fury over Twitter.

'Is it me, or is anyone else shocked at the raunchy performance from
Christina Aguilera, being shown before the watershed?' tweeted Sallywoodings‎.

LottieLovesEwe‎ was similarly taken aback:'Rihanna not so bad but Christina's was just
wrong for 8.30 TV!! seriously inappropriate.'

Predicting
scores of complaints another Twitter user, WhatsAboutTown, posted the
message: 'OMG Christina Aguilera shocking..........how many complaints
will ITV get about #xfactor tonight.'

Raunchy: There were pyrotechnic effects as well as Rihanna's superhot moves

Leaving little to the imagination: It didn't take long for Rihanna to whip off her black and white striped dressing gown and flash the flesh

Another, from x_tinamurhill‎, read:
'Rihanna and Christina's performance on #TheXFactor were very
inappropriate in terms of clothing and dancing. It's a family show.'

Meanwhile
dktom took to Twitter to accuse the two superstars of trying to out do
each other with the raunch factor‎: 'I think Christina and Rihanna are
trying to
out-inappropriate each other. Crikey #xfactor brought me out in a
sweat.'

On popular online TV forum Digital Spy, there was a lot of unease about the explicit nature of the performances on a family show.

Georgiecats said: 'It isn't suitable before 9pm when small children watch this show. I'm no prude but it's too early in the evening for that type of slutty performance.'

Smartie33 agreed, saying: 'Christina and Rhianna - it's just disgusting. It's meant to be a family show.'

Write caption here

Indenile said: 'My son told me the girls (i.e. Christina and her dancers) were being very rude. He would not normally be exposed to this sort of thing and it made him uncomfortable.

'The performance was inappropriate for a family show before the watershed.'

Gwoody said: exactly what i was thinking,both rhiana and christina have sent the equality movement back 40 years this is the reason 11 year old girls think it is ok towear playboy crop tops and jewelery.

'I am far from being a prude, but their "performances" just made me feel a little queasy.'

Rihanna was
performing her new hit What's My Name having earlier taken to the stage
with Cardle to duet on her her Unfaithful number.

Getting on like a house on fire: Rihanna and Matt performed her hit Unfaithful

On fire: Matt could hardly believe his luck when Rihanna demonstrated some of her 'bump and grind' dance moves on him

Meanwhile Christina leant her support to Rebecca as they sang her hit Beautiful together.

The show was expected to receive around 21million viewers. After Cher Lloyd's exit tonight Matt, Rebecca and One Direction will battle it out in the grand finale tomorrow in a bid to win the X Factor crown.

ITV were unavailable for comment last night.

Double
act: Rebecca was joined on stage by Aguilera earlier in the night as they performed a duet of Beautiful